1. Field of the Invention
The present invention relates to a group III nitride compound semiconductor light-emitting device.
The present application is based on Japanese Patent Applications No. 2000-131933 and 2000-154, which are incorporated herein by reference.
2. Description of the Related Art
As described in Unexamined Japanese Patent Publication No. Hei. 11-273571, a light-emitting device is mounted in a cup portion of a mount lead. Electrically conductive wires are connected to the light-emitting device. The light-emitting device is further sealed with a round-type sealing member made of a light-transmissible resin. A light-emitting system configured thus has an optical axis in a direction of the center axis (normal line) of the light-emitting device chip, so that light emitted from the light-emitting device is concentrated in the direction of the optical axis by a forward end half-spherical portion (convex lens portion) of the round-type sealing member. It is, however, impossible to control light coming off the forward end half-spherical portion. Therefore, in order to effectively utilize the light in the direction (in the direction departing from the direction of the center axis), a circumferential wall of the cup portion is provided as a parabolic type wall so that the transverse light is reflected in the direction of the optical axis by the circumferential wall.
A group III nitride compound semiconductor light-emitting device exhibiting emission of light in a range of from blue to green radiates a large quantity of light transversely, in comparison with a red type light-emitting device. In such a group III nitride compound semiconductor light-emitting device large in the quantity of transversely radiated light, how to utilize the transverse light is an importance problem in improvement in light-emitting efficiency of the light-emitting system.
If the reflection surface of the circumferential wall of the background-art cup portion is viewed from this respect, a clearance of from 200 to 300 μm serving as a space for letting a chip-holding jig escape was required to be placed between the chip and the circumferential wall of the cup portion in ordinary design. On the other hand, the thickness of the semiconductor layer in the chip was several μm and the height of the cup portion was limited upon the design of the light-emitting system. Hence, the reflection surface of the circumferential wall of the cup portion could reflect only the transversely radiated light within an angle of elevation of about 10 degrees from a direction perpendicular to the center axis (a right transverse direction).